A technique using a heat sink with pin-like or plate-like fins is widely known as one of techniques for cooling a semiconductor element which generates heat at the time of operation. In addition, for example, a technique for cooling a semiconductor element by passing a refrigerant along a refrigerant flow path formed of a hole, a partition wall, a fin, and the like in a determined member of a cooling jacket or the like thermally connected to the semiconductor element is also known. Cooling systems include an air cooling system and a liquid cooling system which differ in kind of refrigerant used.